Seas Rising at Fastest Rate in Nearly 3K Years

It's "extremely likely" that sea levels rose faster in the 20th century than at any other time in the previous 2,700 years "and the rise over the last two decades has been even faster," scientists say. A new study—based on "reconstructions" of past sea levels from 24 areas around the world, plus tide gauges—finds global sea levels were steady for almost three millennia before they began to rise with the Industrial Revolution, reports USA Today. "We can say with 95% probability that the 20th-century rise was faster than any of the previous 27 centuries," the lead author tells the Washington Post. Sea levels rose 5.5 inches from 1900 to 2000, or about 1.4 millimeters per year. NASA puts the current rate at 3.4 millimeters per year.

Scientists expect sea levels to rise between 9.5 inches and 2 feet by 2100—if we stick to the climate treaty agreed upon in Paris. But a high emissions scenario could see seas rise by more than 4 feet. Another study in Proceedings of the National Academy of Sciences seconds that finding but notes researchers didn't consider the collapse of glaciers of the West Antarctic ice sheet, which "is hypothesized to be already underway." There's no surprise why: Humans burned fossil fuels, which produced greenhouse gases, which melted glaciers and warmed ocean waters, scientists say. If not for humans, sea levels might not have risen at all and thousands of coastal "nuisance" floods in the US would have been avoided, according to Climate Central. (Some 316 US cities may be partially submerged by 2100.)